injectors are making a tapping noise?

[S.A. supra]

Ok here's the story. When I boost some times my car idles funny. It will drop to 300-400 rpms, and the wide band will drop to 11-12. So I open the hood and I can here a tapping noise. Sounds like it is coming from the injectors ( 550 USDM 2JZ ) one more then the others. I can feel the tapping when I touch it. Then after a couple of minutes or so the tapping lessens and the idle returns to normal around 850 rpms. What would cause this?

 

[RockPaperSwoRD]

idle speed control valve. they get stuck closed sometimes and not let enough air in the engine to bring the idle up, so youre running rich at idle. best thing you can do is turn the idle screw on the throttle body to compensate. or you can buy a new 300 dollar iscv..

 

[S.A. supra]

Hey whats up. I'll try that. I know all to well how much those cost. I bought one form my 7m It was like $240 ouch:aigo:

 

[S.A. supra]

But would that explain the tapping. I know that the injectors usually have a tapping sound but the tapping get louder when the car idles low. Then gets quieter when it returns to the normal idle.